Process for oxidative functionalization of polymers containing alkylstyrene

ABSTRACT

This invention provides a method by which an alkylstyrene containing polymer may be exclusively functionalized at the primary benzylic carbon site of the styrenic monomer. The process of this invention comprises the treatment of an alkylstyrene containing polymer dissolved in a non-polar liquid medium with an organic hydroperoxide oxidizing reagent in the presence of a catalytically sufficient amount of a chromium compound, to oxidize a portion of the aromatic alkyl groups of the polymer to an oxygen containing functional group.

This is a divisional of application Ser. No. 08/628,416 filed 5 Apr.1996, now U.S. Pat. No. 5,679,748.

FIELD OF THE INVENTION

This invention relates to polymers containing alkyl styrene monomerunits, the alkyl substituent group(s) of which are functionalized by acatalytic oxidative procedure.

BACKGROUND OF THE INVENTION

Heretofore, butyl rubbers, i.e., polymers of isobutylene and smallamounts of isoprene as a comonomer, and/or halobutyl rubbers, i.e., ahalogenated derivative of a butyl rubber, have been used for formingblend compositions with thermoplastic compounds and other elastomercompounds for use in tire production and the like. The butyl and/orhalobutyl rubbers impart a number of desirable physical properties tosuch blends, such as low air permeability, relatively low glasstransition temperature (T_(g)), broad damping peaks, environmental agingresistance including a resistance to oxidation, etc., that aresignificant in the production of tires of superior performanceproperties. However, various difficulties are encountered with the useof the butyl and/or halobutyl rubbers for this purpose, chief amongwhich is their compatibility with most other polymers, includingunsaturated elastomeric compounds. Hence, that aspect of a butyl rubberthat provides properties which make it desirable as a component inblends for tire production, namely the chemical "inertness" that resultsfrom the unreactiveness of the hydrocarbon backbone of the butyl rubberpolymer, also results in its low reactivity and compatibility with mostother materials and this has limited its use in many areas.

Recently, in U.S. Pat. No. 5,162,445 a unique copolymer of isobutylenehas been disclosed, together with a procedure for introducingnon-backbone functionalities into this copolymer, which well suits it touse as a blend component having all the property advantages of a butyland/or halobutyl rubber, but which improves the compatibility comparedto butyl and/or halobutyl rubber. In its broadest description, the newcopolymer is a direct reaction product of an isoolefin having from 4 to7 carbon atoms with a para-alkylstyrene; isobutylene andparamethylstyrene being the preferred monomers; wherein the copolymerhas a substantially homogeneous compositional distribution, meaning allweight fractions of the copolymer have essentially the same ratio ofisoolefin to para-alkylstyrene. The homogeneity of the comonomerdistribution and molecular weight distribution of this newisobutylene-paraalkylstyrene (IB-AS) copolymer impart to it superiorproperties. One of the aspects in which this new IB-AS copolymer issuperior to butyl rubbers is its resistance to oxidation by atmosphericoxygen and ozone. The new isobutylene-paraalkylstyrene (IB-AS) copolymercan be produced over a broad range of number average molecular weight(M_(n)) greater than 25,000 and a narrow molecular weight distribution(M_(w) /M_(n)) of less than 6.0, even of less than 2.0. Derivatives ofthis new isobutylene-paraalkylstyrene copolymer (IB-AS copolymer) havingfunctionalities that render it compatible and/or cross-linkable withother polymer materials, both thermoplastic and elastomeric polymers,are produced in two step process, by nucleophilic substitution of ahalogenated intermediate that is first produced by a free radicalinitiated halogenation of the IB-AS copolymer.

As related by U.S. Pat. No. 5,162,445, it was found that free radicalbromination of the new IB-AS copolymer proceeded at the alkyl group (thealkyl primary benzylic carbon atom) of the styrenic comonomer and to thesubstantial exclusion of bromination at the tertiary primary benzyliccarbon atom (in the backbone chain of the copolymer). This thenpreserves the initial microstructure of the IB-AS copolymer backbonechain, thus preserving the hydrocarbon nature with its "inertness" ofthe backbone and the beneficial physical properties.

In U.S. Pat. No. 5,162,445 a preferred copolymer is that of isobutylene(IB) and paramethylstyrene (PMS) and this copolymer (IB-PMS) isbrominated to provide a copolymer having a portion of itsparamethylstyrene brominated at the paramethyl group. The brominatedcopolymer is essentially a high molecular weight, narrow molecularweight distribution polymer of a homogeneous distribution ofisobutylene-paramethylstyrene-parabromomethylstyrene. The benzylicbromine atoms are reactive under mild conditions in the presence of anucleophilic reagent. It was found that a variety of functional groupscould be introduced at the site of the brominated paramethyl carbonatoms of the pendant phenyl groups without disruption of the backbonestructure or altering the molecular weight and/or molecular weightdistribution characteristics of this copolymer. This is thenparticularly well suited for use as a blending component with otherthermoplastics and/or elastomeric polymers for use in the fabrication ofdesirable products, especially for tire production.

Though the functionalized derivatives that are realized through thebrominated-copolymer intermediate in two step process, it would bedesirable to provide additional methods for functionalization in asingle step. To convert the new isobutylene-paraalkylstyrene copolymermaterials into functionalized derivatives without the need to employ ahalogen in the process, a metalation procedure was developed asdescribed in commonly owned U.S. patent application Ser. No. 08/446,753.In this procedure the paramethyl group of a paramethylstyrene unit ofthe IB-PMS copolymer is first metallated by a super base reagent andquenched reacted with a suitable electrophile. An advantage of thisprocedure is that it is free from use of any halogen, essentially asingle step process, albeit that it requires the employment of moreexpensive reagents.

Neither the free radical halogenation and then nucleophilic displacementprocedure as described in U.S. Pat. No. 5,162,445 nor the single stepsuper base metalation-electrophilic displacement procedure as disclosedin commonly owned U.S. Ser. No. 08/446,753 provides for the directintroduction of carbonyl functionalities into IB-AS copolymer. Todirectly introduce a carbonyl functionality into an IB-AS copolymerwould require an oxidative procedure.

The oxidation of simple molecules of mono alkyl or multi alkylsubstituted benzene have been reported in a variety of references, suchas Bird, C. W. et al., "A convenient synthesis byp-hydroxybenzaldehydes," Org. Prep. and Procedures Int. 12, 201 (1980);Lee, H. et al., "Benzylic oxidation with2,3-dichloro-5,6-dicyanobenzoquinone in aqueous media. A convenientsynthesis of aryl ketones and aldehydes," J. Org. Chem. 48, 749 (1983);Chidambaram, N. et al., "tert-Butyl hydroperoxide pyridinium dichromate:A convenient reagent system for allylic and benzylic oxidation," J. Org.Chem., 52, 5048 (1978); Capdeville, P. et al., "A new oxidizing copperreagent: CuO₂ H preparation and preliminary study of reactivity,"Tetrahedron Lett. 31, 3891 (1990); Hay, A. S. et al. "Autoxidationreactions catalyzed by cobalt acetate bromide," Canadian J. Chem. 43,1306 (1965); Sala, T. et al. "Tetrabutylammonium permanganet: anefficient oxidant for organic substrates," J. Chem. Soc. Chem. Commun.253 (1978); Muzart, J. et al. "Practical chromium VI oxide-catalyzedbenzylic oxidations using 70% tert-butylhydroperoxide," TetradedronLetts. 23, 2132 (1987); Zhang, S. et al., "Selective indirectelectrooxidation of the side chain of aromatic compounds," Chin. Chem.Lett. 3(8), 595 (1992); Shul'pin, B. G. et al., "Photoinduced reactionsof organic compounds with transition metal complexes. Oxidation ofalkanes and alkylbenzenes with oxo compounds of chromium (VI) underirradiation with light," Zh Obscheh. Khim. 59(11), 2604 (1989). Hronec,M. et al, "Kinetics and mechanism of cobalt-catalyzed oxidation ofp-xylene in the presence of water," Ind. Eng. Chem. Process Des. Dev.23, 787-794 (1985); Hendricks, C. et al, "The oxidation of substitutedtoluenes by cobalt (III) acetate in acetic acid solution," Ind. Eng.Chem. Prod. Res. Dev. 17(3), 256-260 (1978); Hanotier, J. et al.,"Effect of strong acids on the oxidation of alkylarenes by manganic andcobaltic acetates in acetic Acid," J. Chem. Soc. Perkins Trans. 2,381-383 (1973); Okada, T. et al., "The liquid-phase oxidation ofmethylbenzenes by the cobalt-copper-bromide system," Bull. Chem. Sos.Jpn. 54, 2724-2727; Harustiak, M. et al., "Kinetics and mechanism ofcobalt bromide catalyzed oxidation of p-xylene in the presence of phasetransfer catalysts," J. Mol. Catal. 53(1), 209-217. Alkyl substitutedbenzenes in the presence of a polar medium, such as acetic acid,reported to be oxidized by chromic oxide, cobalt salts, manganic andcobaltic acetates, and cobalt-copper-bromide systems. Although suchsystems are applicable to molecular materials, such as toluene, xylene,etc., they are not applicable to polymeric materials, such as alkylstyrene containing polyolefin, which is highly non-polar and thereforeessentially insoluble in the polar reaction medium.

The liquid phase oxidation of homopolymer of para-methylstyrene (PMS)using air as an oxidizing agent in the presence of a bromine promotedcatalyst has been reported by Stover et al. U.S. Pat. No. 5,376,732(1994) and WO 94/10215 publication. This procedure as described by theStover patent and/or the related paper of Ferrari, L. et al.,"Cobalt-catalyzed oxidation of poly(4-methylstyrene)," Macromolecules,24, 6340-6342 (1991), requires use of a cosolvent medium containingacetic acid. The presence of acetic acid as a required component in thecosolvent medium severely limits the quantity of precursor polymer thatmay be treated, generally to concentrations significantly less than 5 gmper 100 ml. The maximum molecular weight of a precursor polymer reportedto be treated by this method, as described in U.S. Pat. No. 5,376,732,is a weight average molecular weight (Mw) of 14,600 and Mw/Mn =1.71.This limitation is readily attributable to the poor solubility of theprecursor polymer in a medium in which acetic acid is a cosolvent.

It is still desirable to devise a simple, direct and inexpensive way bywhich to convert the new IB-AS copolymer materials into functionalizedderivatives without the need to employ a halogen or halogenatedcompounds, acetic acid or other polar cosolvents in the process.

A method of functionalization is necessary for IB-alkylstyrene (AS)copolymer in which alkyl group may be in ortho, meta, or para position,including multi alkyl groups at random in any position of the aromaticring.

SUMMARY OF THE INVENTION

This invention provides a method by which an alkylstyrene containingpolymer, for example, an isobutylene-alkylstyrene (IB-AS) copolymer, maybe functionalized at the primary benzylic carbon site of the styrenicmonomer without the need to employ a halogen or halogenated compound,acetic acid or other polar compounds as a cosolvent. As described withrespect to an IB-AS copolymer, the method comprises treating thecopolymer while in solution in a non-polar medium, such as a hydrocarbonsolvent, to the action of an effective catalytic amount of a chromiumcompound capable of performing as an oxidation catalyst, preferably a Cr(VI) compound such as chromium oxide (CrO₃) or a Cr compound thatoxidizes to Cr (VI) during the catalytic action, and an effective amountof an organic hydroperoxide, preferably an alkyl hydroperoxide, tooxidize alkyl group at the primary benzylic carbon atom of the styreneunits of the copolymer to a carbonyl functional group.

With the method of this invention it is now possible to introducecertain types of carbonyl atom functional groups into theisobutylene-alkylstyrene copolymer which cannot be introduced throughthe bromination and then nucleophilic displacement procedure asdescribed in U.S. Pat. No. 5,162,445 or the metalation-electrophilicreagent procedure described in U.S. Ser. No. 446,753. Further, theoxidative procedure of this invention is not subject to the deficienciesof previously described oxidative procedures which preclude theireffective application to high molecular weight polymeric materialscontaining alkylsytrenes, namely the requirement of a polar cosolventcomponent that severely reduces the solubility of such polymericmaterials. In the oxidative procedure of this invention a polarcosolvent is not used and the precursor polymer may be treated as a highconcentration solution, making the oxidative procedure of this inventionapplicable to treatment of all compositions of isoolefin-alkylstyrene(ISO-AS). The oxidative procedure of this invention is particularlyeffective for oxidizing an isobutylene-alkylstyrene copolymer (IB-AS)which is otherwise resistant to oxidation by techniques employed onsimple alkylstyrene molecules of homopolymers. The process is versatilein the sense that more than one alkyl substituted styrene containingcopolymer may be oxidized to carbonyl functionality at one or more alkylsite of the aromatic ring. As a matter of fact, homopolymers of mono ormulti alkyl substituted styrene may be effectively oxidized also.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention comprises a method for converting amono or multi alkylsubstituted styrene containing precursor polymer to a product polymer inwhich a fraction of the alkyl groups of the styrene unit in homo- or co-polymer are converted into a carbonyl atom functional group. Theconversion of an alkylsytrene monomer contained by a precursor polymerwhich is accomplished by practice of this invention may be illustratedas follows: ##STR1## wherein:

P represents the remainder of the polymer chain of the precursorpolymer.

R¹ is hydrogen or an alkyl group preferably having 1 to 8 carbon atoms,

R² is hydrogen, alkyl (preferably having from 1 to 8 carbon atoms) or ahydroxyl group, and

R³ is an alkoxy, amino, halogen or metal group.

The precursor polymer, formula I, is first oxidized to a product polymerin which the primary benzylic carbon atom of the alkyl group of thestyrene monomer is oxidized to a carboxylic acid and an aldehyde group,represented by formula II. The conditions of the oxidation reactiondetermine which derivative, the aldehyde or the carboxylic acid,predominate. This product polymer (I) may be recovered and used as suchor it may be further reacted with an alcohol, amine, acid halide or abase to convert the carbonyl functional group thereof to an ester,amide, acid halide or carboxylic salt functional group as represented byformula (III).

The precursor polymer may be a homo or copolymer of an alkylstyrene inwhich the alkyl group is located at any position, ortho, meta or para,on the phenyl ring. The alkyl group may be one or more in the ortho,meta, and/or para position of the phenyl ring. Typically, the precursorpolymers are polyalkylstyrenes, such as poly-p-alkylstyrene,poly-o-alkylstyrene poly-m-alkylstyrene, poly-2,4-alkylstyrene,poly-2,5-alkylstyrene, wherein the alkyl groups can have from 1 to 8carbons, preferably 1 to 4 carbon atoms, and most preferably 1 or 2carbon atoms; isoolefin-alkylstyrenes copolymers wherein the isoolefincan have from 1 to 7 carbon atoms and the alkyl group can have from 1 to8 carbon atoms such as isobutylene-p-methylstyrene copolymers,isobutylene-m-styrene copolymers, isobutylene-o-methylstyrenecopolymers, isobutylene-p-ethylstyrene copolymers,isobutylene-o-ethylstyrene, isobutylene-m-ethylstyrene copolymers,isobutylene-2,5-methylstyrene copolymers, isobutylene-2,4-methylstyrenecopolymers and mixtures thereof such as a mixture ofisobutylene-p-methylstyrene copolymers and isobutylene-o-methylstyrenecopolymers. The precursor polymer may be of any molecular weight, ashigh as 1,000,000 or even greater, limited only by a necessity that theprecursor polymer must be soluble to some degree in a non-polar medium,such as a hydrocarbon solvent. The process of this invention isparticularly useful with respect to copolymers of an isoolefin and analkylstyrene wherein the isoolefin content of the copolymer is about 50mole % or greater of the copolymer and preferably 50-90 mole % of thecopolymer. Such copolymers of an alkylstyrene are generally resistant tooxidation, which is one of their properties that makes them desirablefor use in various applications, and heretofore it has not been possibleto produce functionalized derivatives of such copolymers by an oxidationprocedure.

Precursor polymers of particular interest are those wherein the alkylsubstituent of the styrene monomer are located in the para position,such as poly(4-alkylstyrenes) and isoolefin-paraalkylstyrene copolymers.Of these the isoolefin-para-alkylstyrene copolymers are of particularinterest and the process of this invention will hereafter be describedwith reference to these copolymers, although it should be understoodthat the process is applicable to the other classes of homo andcopolymer precursors as described.

In an embodiment of this invention there is provided a processcomprising the treatment of an isoolefin-alkylstyrene (ISO-AS) copolymerdissolved in a non-polar liquid medium with an organic hydroperoxideoxidizing reagent in the presence of a catalytically sufficient amountof a chromium compound, such as CrO₃, in order to oxidize a fraction ofthe alkyl groups of the alkylstyrene to an oxygen containing functionalgroup. In one embodiment, this invention provides for the oxidation ofthe primary benzylic carbon of the alkyl group of the styrenic comonomerunit. The degree to which the alkylstyrene content of the precursorcopolymer is converted to an oxygen containing functionalized derivativemay be conveniently controlled through appropriate selection of theconditions of reaction such as the organic hydroperoxide concentration,catalyst amount and/or the time and temperature of the reaction.

The isoolefin-alkylstyrene (ISO-AS) particularly preferred forapplication of the oxidative-functionalization process of this inventionare those as described in U.S. Pat. No. 5,162,445, the disclosure ofwhich is hereby incorporated by reference as if fully set forth anddescribed herein for purposes of U. S. patent practice. Those copolymersof particular interest, and hence the preferred copolymers, are those ofisobutylene (IB) and alkylstyrene (AS) and particularly those ofisobutylene and paramethylstyrene (PMS), which may hereafter be referredto as an IB-PMS copolymer. Of these IB-PMS copolymers, the mostpreferred are the IB-PMS copolymers that exhibit elastomeric properties.The more preferred elastomeric IB-PMS copolymers have an isobutylenecontent of from about 80 to 96 weight percent (about 89 to 98 mole %)and a paramethystyrene content of about 20 to 4 weight percent (about11-2 mole %). Generally, the elastomeric IB-PMS copolymers have a numberaverage molecular weight (M_(n)) of 500 or greater, preferably of 25,000or greater, ranging up to about 2,000,000 and their molecular weightdistribution is less than 6.0, preferably less than 4.0, and mostpreferably less than 2.5. Preferably the M_(n) is between 80,000 and1,000,000.

The high molecular weight IB-PMS elastomeric copolymers, whenfunctionalized in accordance with this invention, retain their superiorrubber properties and are especially useful and desired as compoundedrubber compositions and as blending components for the formulation ofblend compositions with other thermoplastic and/or elastomeric polymersused in the production of carcass, side wall, tread and other componentsof pneumatic tires having superior performance properties. The lowermolecular weight IB-PMS elastomeric copolymers when functionalized bythe process of this invention are particularly useful as lube oiladditives and adhesives.

Solvents which may be employed as the neutral non-polar liquid mediumfor reaction are one or more hydrocarbon solvents that have boilingpoints from about 0° C. to about 200° C. The hydrocarbon solvent can bebenzene or an aliphatic or cydoaliphatic hydrocarbon and preferably is ahydrocarbon in which the IB-AS copolymer is soluble to at least theextent of about 5 gm per 100 ml. Among the suitable solvents, preferredsolvents include pentane, n-hexane, heptane, octane, nonane, decane,cyclohexane, methylcydohexane, and the like.

The oxidizing agent for this procedure may be any organic hydroperoxidewhich is sufficiently soluble in the selected non-polar medium toprovide for a soluble concentration of the organic hydroperoxide that,with reference to the alkyl styrene content of the IB-AS copolymerdissolved in the medium, provides for a molar ratio of hydroperoxide toalkyl styrene of from about 8 to about 25.

Illustrative of the preferred organic hydroperoxides for use are1,1-dimethylethyl hydroperoxide t-butyl hydroperoxide!;1,1-dimethylpropyl hydroperoxide t-amyl hydroperoxide!;1,1,3,3-tetramethylbutyl hydroperoxide; and(1,1,4,4-tetramethyl-1,4-butadienyl)bis hydroperoxide. Of these t-butylhydroperoxide is the most preferred for use as the oxidizing agent.

The organic hydroperoxide selected for use may be directly used in itscommercially available form--generally as a 5.0 to 6.0M solution of thehydroperoxide in decane or nonane.

The catalyst for the oxidation reactions may suitably be any chromiummoiety, oxidizable to Chromium VI under the conditions for oxidizing thealkyl group, and which is soluble in the non-polar reaction medium whenmixed with an organic hydroperoxide. Suitable chromium compounds whichmay serve as a catalyst include chromium trioxide (CrO₃); variousco-ordinate ligand derivatives of chromium tetra carbonyl, such asCr(CO)₄ X wherein coordinate ligand X is 1,10 phenanthroline,2,2'-dipyridyl, ethylenediamine, cydohexane-1,2-diamine or2,5-dithiahexane; coordinate ligand derivatives of chromium tricarbonyl,such as Cr(CO)₃ Y wherein coordinate ligand Y is diethylenetriamine or3,6,9-trithiaundecane; chromyl oxides like CrO₂ Z₂ where Z is acetate,benzoate or the like; chromium anhydride compounds of the formula:##STR2## where R' is an alkyl group and each R' is preferably a methyl.Of these the most preferred as the catalyst for reaction is CrO₃.

In its most general application the process of this invention ispracticed by bringing the IB-AS copolymer, oxidizing reagent andcatalyst together in solution in a non-polar liquid medium under acondition of temperature and for a time sufficient to affect oxidationof at least about 5 mole % of the AS content available in the non-polarliquid medium solution. The oxidization reaction will proceed attemperatures as low as 0° C., albeit at a slow rate. Hence, it ispreferred to conduct the reaction at a temperature of at least 10° C.,and more preferably at least 20° C. Generally it is not beneficial ordesirable to exceed a temperature of about 60° C. for the reaction. Thereactants it may be maintained in contact for any length of timedesired. Generally, in the temperature range of 20° C. to 60° C. for thereaction, the degree of reaction desired may be achieved within acontact period of about 8 to about 20 hours.

The order in which any of the respective components--precursor polymer,oxidizing agent, catalyst--are first brought into solution in thenon-polar medium can be any. For convenience, the IB-AS copolymer maybe, and preferably is, first dissolved in the non-polar medium in anamount to provide for the concentration of copolymer desired, up to andincluding that amount corresponding to its solubility limitedconcentration in the medium selected.

Hence, it is preferred to utilize the IB-AS copolymer in solutionconcentrations of at least about 5 gm per 100 ml., and more preferablyin concentrations of 10 to 20 gm per 100 ml. Once the polymer solutionis prepared, either or both of the catalyst and oxidizing agent may beadded to the solution, together or separately, preferably with stirringor mixing of the solution during and following their addition. Inanother embodiment, the catalyst composition may be added to theconcentration in which the catalyst is desired to be present andthereafter the organic hydroperoxide may be added. In anotherembodiment, the catalyst and oxidizing agent may be added to the polymersolution while maintaining the solution at the temperature at which itis desired to conduct the oxidation reaction or, if the mediumtemperature is lower during the course of these additions it may beelevated to the temperature desired for the reaction following theiraddition.

The quantity of catalyst and organic hydroperoxide to be used is mostconveniently expressed as a mole % or molar ratio relative to thealkylstyrene content of the IB-AS copolymer being treated. Hence, forthe desired degree of conversion of AS groups to be achieved within areasonable frame of time (24 hours or less) the catalyst compositionshould be used in a quantity which provides for at least about 1 mole %of catalyst relative to the AS content. The catalyst quantity may, butpreferably does not exceed about 15 mole % of the AS content. Whereinthe catalyst is CrO₃ it is preferably employed in an amount thatprovides for from about 5 to about 10 mole % of PMS content of IB-PMScopolymer.

Generally, the organic hydroperoxide oxidizing agent may be used in anamount which provides a mole ratio of hydroperoxide to the AS content ofthe copolymer undergoing treatment of at least about 8:1. For a giventime and temperature of the reaction the quantity of AS converted byoxidation to a functionalized group will increase as the quantity oforganic hydroperoxide utilized increases, up to a mole ratio ofhydroperoxide to the AS content of the copolymer undergoing treatment ofabout 25:1. Utilization of quantities of organic hydroperoxide beyondthis amount does not significantly increase the degree of conversion.

Within the above described concentration ranges for the IB-AS copolymer,catalyst and organic hydroperoxide components the oxidation reactionwill occur within a range of temperature of from about 20° C. to about50° C. to affect a conversion of from about 5 to about 50 mole % of theAS content available for reaction within a period of time ranging fromabout 8 to about 24 hours. The resulting oxidation product is anisobutylene-methylstyrene-vinylbenzoic acid terpolymer, with traceamounts of vinylbenzaldehyde which possesses a M_(w) /M_(n) and a numberaverage molecular weight which substantially corresponds to that of theprecursor IB-methylstyrene (MS) copolymer.

The product polymer resulting from the oxidation of the IB-AS copolymeris a IB-AS-vinylbenzoic acid terpolymer. The terpolymer product whichmay be recovered as such or it may be further reacted with anotherreagent to convert all or part of its carboxylic functional group to anacid halide, amide, ester, or carboxylic salt functional group.

EXAMPLES

The following examples illustrate practices in accordance with theprocess of this invention. Unless otherwise stated, molecular weightsreported as Mn and Mw were determined by Gel Permeation Chromatography(GPC), respectively. The percentage of PMS content of a IB-PMS copolymerwas determined by ¹ H NMR. The acid content of a product polymer wasdetermined by ¹ H NMR and FTIR.

In each of Example 1-7 which follow the precursor polymer used was anisobutylene-paramethylstyrene copolymer (IB-PMS), which had a content ofisobutylene of 97.5 mole % and a content of paramethylstyrene of 2.5mole %. The precursor polymer had a weight average molecular weight(M_(w)) of 35,000 and a molecular weight distribution (M_(w) /M_(n)) of3.5.

Example 1

To a 20 gm per 100 ml solution in dry n-hexane of an IB-PMS copolymer,having an IB content=97.5 mole %, a PMS content=2.5 mole %, M_(w)=35,000, and a molecular weight distribution (M_(W) /M_(N))=3.5, acatalytic amount of CrO₃ (0.004 g/gm of polymer i.e., about 10 mole % ofPMS unit) was added and stirred under an argon atmosphere. To thissolution t-butyl hydrohydroperoxide (5M solution in decane) was thenadded in an excess of 15 times the molar amount of PMS unit. Thereaction was conducted at 45°-50° C. for 20 hours.

The product was washed with 50% HCl saturated NaCl solution, and 5 timeswith acetone water (20/80 v/v) to near neutral. Finally, the productpolymer was precipitated in acetone, washed with acetone and dried at60°-65° C. for 2 days. ¹ H NMR and FTIR indicated --COOH functionality,and conversion was about 40% of total PMS content of the startingcopolymer. GPC results indicated that the product polymer had M_(w)=28,000 and a M_(w) /M_(n) =4.7.

Example 2

The same IB-PMS copolymer as in Example 1 was prepared as a 5 gm per 100ml solution in dry n-hexane (3.47g polymer in 70 ml n-hexane). To thissolution 14 mg of CrO₃ (about 10 mole % of PMS) was added with stirringunder an argon atmosphere while the solution was maintained at 40°-45°C. Thereafter 5.5 ml of 5M t-butyl hydroperoxide in decane was added tothe solution and the reaction was conducted at 45°-50° C. for 25 hours.Recovery of the product and drying were carried out under identicalcondition as Example 1. ¹ H NMR and FTIR indicated --COOH functionalityand a conversion of about 20.5% of the total PMS content of the startingcopolymer.

Example 3

Effect of Reaction Temperature

The same reaction conditions of Example 2 were followed with theexception that the reaction was conducted at 60° C. As t-butylhydroperoxide was added to the solution of IB-PMS copolymer at 60° C.,it started to decompose (visible vigorous bubbling observed). Noreaction of the IB-PMS copolymer to a --COOH functional derivative wasfound to have occurred after 4 hours. This example demostrates that hightemperature is undesirable.

Example 4

A 5 gm per 100 ml solution of the IB-PMS copolymer of Example 1 in dryn-hexane (3g IB-PMS copolymer in 60 ml hexane) was prepared and 12 mg ofCrO₃ was added to this solution with stirring under an argon atmosphere.Thereafter 2 ml of 5M t-butyl hydroperoxide in decane was added to thesolution and the reaction was conducted at 45°-50° C. for 12 hours afterwhich a first aliquot of the reaction solution was drawn off andthereafter an additional 2 ml of the 5M tertbutyl hydroperoxide solutionwas added and the course of reaction was continued at 45°-50° C. forfurther 15 hours, after which the reaction was ended and the productpolymer was recovered under the same conditions as described in Example1.

¹ H NMR and FTIR analysis of the product polymer sampled after the endof 12 hours revealed that about 15% of PMS content of the startingcopolymer has undergone conversion to a --COOH functionality. The finalproduct polymer analyzed to have about 20% of the starting copolymer PMScontent converted to --COOH functionality.

Example 5

Comparative

The same IB-PMS copolymer as in Example 1 was added to a cosolventsystem of 15 ml dry n-hexane containing 1 ml acetic acid. The maximumconcentration of dissolved IB-PMS copolymer that could be achieved was0.56 g in 16 ml cosolvent or about 3.5 gm per 100 ml To this 3.5 gm per100 ml IB-PMS copolymer solution cobalt acetate tetrahydrate was addedin an amount to provide a molar ratio to the PMS content of thedissolved copolymer of 1:1. The solution was heated to 60° C. andthereafter O₂ was bubbled through the solution under stirring for 15hours. At the conclusion of this time, the solution was treated asdescribed in Example 1 to recover polymer. ¹ H NMR and FTIR analysiswere performed on the recovered polymer and revealed that no detectableportion of the PMS content of the starting copolymer had been convertedto --COOH functionality.

The procedure was repeated, except that NaBr was added in an amountequal to one equivalent of cobalt acetate tetrahydrate. Again ¹ H NMRand FTIR revealed no detectable portion of the PMS content had beenconverted to --COOH functionality.

Example 6

The same reaction of Example 5 was repeated except that 7 mg of CrO₃ wasadded instead of cobalt acetate tetrahydrate. All other conditions werethe same as for Example 5 and the same results were observed, namely nodetectable portion of the PMS content of the starting IB-PMS copolymerwas converted to --COOH functionality.

Example 7

IB-PMS copolymer as in Example 1 was dissolved in dry n-hexane and thenCrO₃ was added. Then 4 ml t-BuOOH (5M solution in decane) containing atrace of water added. It did not dissolve CrO₃ completely. A further 1.5ml of the t-BuOOH solution was added, and the reaction was conducted at40°-45° C. for 25 hours, and then at 60° C. for 2 hours. The product waswashed with 50% HCl, isopropyl alcohol/H₂ O and precipitated inisopropyl alcohol. It was then dried at 80°-85° C. for 3 days. ¹ H NMRanalysis established that a conversion of 25.4 mole % of the PMS contentto a --COOH functionality had occurred.

Example 8

Oxidation of Homopolymer

Poly(para-methylstyrene) of molecular weight, M_(w) =517,800 andmolecular weight distribution (M_(W) /M_(n)) of 1.98 was dissolved incyclohexane to obtain a 5 gm per 100 ml solution under argon atmosphere.To this solution a catalytic amount of CrO₃ ((1 mole % of PMS unit) wasadded, and then t-butyl hydroperoxide (5M solution in decane) was addedin excess of 10 times the molar amount of PMS unit. The reaction wasconducted at room temperature (20°-25° C.) for 25 hours. The product waswashed with dilute HCl. The organic layer was evaporated and the solidpolymer thus obtained was dissolved in tetrahydrofuran. The pure polymerwas recovered by precipitation in water. It was reprecipitated fromtetrahydrofuran to water, dried under vacuum at 50° C. for 2 days. FTIRand ¹ H NMR indicated oxidation to --COOH functionality and a smallamount of --CHO. The conversion was about 30 mole % of PMS unit. Themolecular weight of the product, as obtained by GPC, indicated to beM_(w) =225,500, and M_(w) /M_(n) =3.3.

Example 9

Effect of Molecular Weight

To find the effect of oxidation on the molecular weight, a very highmolecular weight IB-PMS copolymer was oxidized following the procedureas set forth in the previous examples. The high molecular weight IB-PMScopolymer having an IB content=96.3 mole % and para-methylstyrenecontent=3.7 mole %, M_(w) =517,300 and a molecular weight distribution,M_(w) /M_(n) =2.4, was dissolved in cyclohexane to obtain a 5 gm per 100ml solution under an argon atmosphere. To this stirring solution acatalytic amount of CrO₃ (10 mole % of PMS) was added and followed byaddition of t-butyl hydroperoxide (5M solution in decane) in an excessof 10 times of the molar amount of PMS. The reaction was conducted atroom temperature for 22 hours. The product was recovered by the usualprocedure as mentioned in Example 1. FTIR and ¹ H NMR indicated --COOHfunctionality with conversion of about 10% of total PMS unit. Themolecular weight of the material was measured to have M_(w) =417,600 andM_(w) /M_(n) =2.20.

Example 10

The same high molecular weight IB-PMS copolymer as in Example 9, wasprepared as a 5 gm per 100 ml solution in cyclohexane under a nitrogenatmosphere. The solution was heated in an oil bath to 45° C. whilestirring by magnetic stirrer. Then a catalytic amount of CrO₃ (10 mole %of PMS), and 15 times excess (of PMS unit) of t-butyl hydroperoxide (5Msolution in decane) was added while stirring continued moderately. Thereaction was conducted for 24 hours, and the oxidized product wasrecovered following the procedure as in Example 1. The FTIR and ¹ H NMRshowed substantial oxidation of PMS unit to about 30 mole %. The GPCresult indicated M_(w) =362,300 and molecular weight distribution, M_(w)/M_(n) =2.35.

Although the invention has been described by reference to its preferredembodiments, from this description those having ordinary skill in theart may appreciate changes and modifications that may be made to thesubject matter described which does not depart from the scope and spiritof the invention as described above or claimed below.

We claim:
 1. A polymer having a molecular weight of about 80,000 orgreater comprising isobutylene-paramethylstyrene-paracarbonylstyrenemonomeric units.
 2. The composition of claim 1, wherein theparacarbonylstyrene comprises a carbonyl group which is an aldehyde,amide, acid halide, ester or carboxylic salt.